How Much Carbohydrates Should We Eat?

Written by Dr. Steve Chaney on . Posted in carbohydrates

The “Goldilocks Effect”

Author: Dr. Stephen Chaney

 

How much carbohydrates should we eat?

how much carbohydrates should we eatThe low-carb wars rage on. Low-carb enthusiasts claim that low-carb diets are healthy. Many health experts warn about the dangers of low-carb diets. Several studies have reported that low-carb diets increase risk of mortality (shorten lifespan).

However, two recent studies have come to the opposite conclusion. Those studies reported that high carbohydrate intake increased mortality, and low carbohydrate intake was associated with the lowest mortality.

One of those studies, called the Prospective Urban Rural Epidemiology (PURE) study was published just last year. It included data from 135,335 participants from 18 countries across 5 continents. That’s a very large study, and normally we expect very large studies to be accurate. The results from the PURE study had low-carb enthusiasts doing a victory lap and claiming it was time to rewrite nutritional guidelines to favor low-carb diets.

Whenever controversies like this arise, reputable scientists are motivated to take another look at the question. They understand that all studies have their weaknesses and biases. So, they look at previous studies very carefully and try to design a study that eliminates the weaknesses and biases of those studies. Their goal is to design a stronger study that reconciles the differences between the previous studies.

how much carbohydrates should we eat studySuch a study has just been published (SB Seidelmann et al, The Lancet, doi.org/10.1016/S2468-2667(18)30135-X ). This study resolves the conflicting data and finally answers the question: “How much carbohydrates should we be eating if we desire a long and healthy life?” The answer is “Enough.”

I call this “The Goldilocks Effect” You may remember “Goldilocks And The Three Bears.” One bed was too hard. One bed was too soft. But, one bed was “just right.” One bowl of porridge was too hot. One was two cold. But, one was “just right.”  According to this study, the same is true for carbohydrate intake. High carbohydrate intake is unhealthy. Low carbohydrate intake is unhealthy. But, moderate carbohydrate intake is “just right.”

How Was The Study Done?

This study was performed in two parts. This first part drew on data from the Atherosclerosis Risk in Communities (ARIC) study. That study enrolled 15,428 men and women, aged 45-64, from four US communities between 1987 and 1989. This group was followed for an average of 25 years, during which time 6283 people died. Carbohydrate intake was calculated based on food frequency questionnaires administered when participants enrolled in the study and again 6 years later. The study evaluated the association between carbohydrate intake and mortality.

The second part was a meta-analysis that combined the data from the ARIC study with all major clinical studies since 2007 that measured carbohydrate intake and mortality and lasted 5 years or more. The total number of participants included in this meta-analysis was 432,179, and it included data from both studies that claimed low-carbohydrate intake was associated with decreased mortality.

 

How Much Carbohydrates Should We Eat?

 

how much carbohydrates should we eat ripThe results from the ARIC study were:

  • The relationship between mortality and carbohydrate intake was a U-shaped curve.
  • The lowest risk of death was observed with a moderate carbohydrate intake (50-55%). This is the intake recommended by current nutrition guidelines.
  • The highest risk of death was observed with a low carbohydrate intake (<40%).
  • The risk of death also increased with very high carbohydrate intake (>70%).
  • When the investigators used the mortality data to estimate life expectancy, they predicted a 50-year old participant would have a projected life expectancy of:
  • 1 years if they had a moderate intake of carbohydrates.
  • Their life expectancy was 4 years less if they had a low carbohydrate intake.
  • Their life expectancy was 1.1 year less if they had a very high carbohydrate intake.
  • The risk associated with low carbohydrate intake was affected by what the carbohydrate was replaced with.
  • When carbohydrate was replaced with animal protein and animal fat there was an increased risk of mortality on a low-carb diet. The animal-based low-carb diet contained more beef, pork, lamb, chicken and fish. It was also higher in saturated fat.
  • how much carbohydrates should we eat plantbasedWhen carbohydrate was replaced with plant protein and plant fats, there was a decreased risk of mortality on a low-carb diet. The plant-based low-carb diet contained more nuts, peanut butter, dark or whole grain breads, chocolate, and white bread. It was also higher in polyunsaturated fats.
  • The effect of carbohydrate intake on mortality was virtually the same for all-cause mortality, cardiovascular mortality, and non-cardiovascular mortality.
  • There was no significant affect of carbohydrate intake on long-term weight gain (another myth busted).

The results from the meta-analysis were very similar. When the data from all studies were combined:

  • Both low carbohydrate diets and very high carbohydrate diets were associated with increased mortality.
  • Meat-based low-carb diets increased mortality, and plant-based low-carb diets decreased mortality.
  • Once again, the results were the same for total mortality, cardiovascular mortality, and non-cardiovascular mortality.

The authors concluded: “Our findings suggest a negative long-term association between life-expectancy on both low carbohydrate and high carbohydrate diets…These data also provide further evidence that animal-based low carbohydrate diets should be discouraged. Alternatively, when restricting carbohydrate intake, replacement of carbohydrates with predominantly plant-based fats and proteins could be considered as a long-term approach to healthy aging.”

Why Were Some Previous Studies Misleading?

This study also resolved the discrepancies between previous studies. The authors pointed out that the average carbohydrate intake is very different in Europe and the US than in Asian countries and low-income countries. In the US and Europe, mean carbohydrate intake is about 50% of calories and it ranges from 25% to 70% of calories. With that range of carbohydrate intake, it is possible to observe the increase in mortality associated with both low and high carbohydrate intakes.

White rice is a staple in Asian countries, and protein is a garnish rather than a main course. Consequently, overall carbohydrate intake is greater in Asian countries and very few Asians eat a low carbohydrate diet. High protein foods tend to be more expensive than high carbohydrate foods. Thus, very few people in developing countries can afford to follow a low carbohydrate diet, and overall carbohydrate intake also tends to be higher.

how much carbohydrates should we eat aricTherefore, in Asian and developing countries the average carbohydrate intake is greater (~61%) than in the US and Europe, and the range of carbohydrate intake is from 45% to 80% of calories. With that range of intake, it is only possible to see the increase in mortality associated with high carbohydrate intake.

Both the studies that low-carb enthusiast quote to support their claim that low-carb diets are healthy relied heavily on data from Asian and developing countries. In fact, when the authors of the current study overlaid the data from the PURE study with their ARIC data, there was an almost perfect fit. The only difference was that their ARIC data covered both low and high carbohydrate intake while the PURE study touted by low-carb enthusiasts only covered moderate to high carbohydrate intake. [I have given you my rendition of the graph on the left. If you would like to see the data yourself, look at the paper .]

Basically, low-carb advocates are telling you that diets with carbohydrate intakes of 30% or less are healthy based on studies that did not include carbohydrate intakes below 40%. That is misleading. The studies they quote are incapable of detecting the risks of low carbohydrate diets.

What Does This Mean For You?

There are several important take-home lessons from this study:

  • All major studies agree that very high carbohydrate intake is unhealthy. In part, that reflects the fact that diets with high carbohydrate intake are likely to be high in sodas and sugary junk foods. It may also reflect the fact that diets which are high in carbohydrate are inevitably low in protein or healthy fats or both.
  • how much carbohydrates should we eat low-carbAll studies that cover the full range of carbohydrate intake agree that low carbohydrate intake is also unhealthy. It shortens life expectancy of a 50-year old by about 4 years.
  • The studies quoted by low carb enthusiasts to support their claim that low-carb diets are healthy don’t include carbohydrate intakes below 40%. That means their claims are misleading. The studies they quote are incapable of detecting the risks of low carbohydrate diets.
  • Meat-based low-carb diets decrease life expectancy while plant-based low carb diets increase life expectancy. This is consistent with previous studies. For more details on those studies, see my article “Are Any Low-Carb Diets Healthy?” in “Health Tips From The Professor” or my book, “Slaying The Food Myths.”

The health risks of meat-based low-carb diets may be due to the saturated fat content or the heavy reliance on red meat. However, the risks are just as likely to be due to the foods these diets leave out – typically fruits, whole grains, legumes, and some vegetables. Proponents of low-carb diets assume that you can make up for the missing nutrients by just taking a multivitamin. However, each food group also provides a unique combination of phytonutrients and fibers. The fibers, in turn, influence your microbiome. Simply put, whenever you leave out whole food groups, you put your health at risk.

Limitations Of This Study

how much carbohydrates should we eat limitationsMy main concern with this study and all previous studies is that they lump all carbohydrates together, as if they were equally healthy or unhealthy. We should really be focusing on healthy carbohydrates versus unhealthy carbohydrates, healthy proteins versus unhealthy proteins, and healthy fats versus unhealthy fats. We should be focusing on foods.

For example, the plant-based low carbohydrate diets in this study probably had a higher percentage of healthy carbohydrates because those diets feature whole, plant-based foods. The very high carbohydrate diets in this study probably had a higher percentage of unhealthy carbohydrates. However, we have no idea whether the diets with moderate carbohydrate intake featured healthy carbohydrates or unhealthy carbohydrates. That is critical because moderate carbohydrate intake was the baseline to which all other diets were compared.

An important unanswered question is: “What is the relationship between carbohydrate intake and lifespan when most of the carbohydrates come from whole, plant-based foods?” Is low carbohydrate intake healthier or less healthy than moderate carbohydrate intake? Is high carbohydrate intake still less healthy? We have no idea. No studies have analyzed the data in that way.

Similarly, we know from multiple studies that meat-based, low-carb diets increase mortality and plant-based, low-carb diets decrease mortality when compared to moderate carbohydrate intake with no differentiation of protein source. But, what if the moderate carbohydrate group had also been subdivided into meat eaters and plant eaters? Would meat-based, low-carb diets still be less healthy than meat-based, moderate-carbohydrate diets? Would plant-based,  low-carb diets still be healthier than plant-based, moderate-carb diets? We have no idea.

 

The Bottom Line

The low-carb wars are raging. Several studies have reported that low-carb diets increase risk of mortality (shorten lifespan). However, two recent studies have come to the opposite conclusion. Those studies have low-carb enthusiasts doing a victory lap and claiming it is time to rewrite nutritional guidelines to favor low-carb diets.

However, a study just published a couple of weeks ago resolves the conflicting data and finally answers the question: “How much carbohydrate should we be eating if we desire a long and healthy life?” The answer is “Enough.”

I call this “The Goldilocks Effect.”  According to this study, high carbohydrate intake is unhealthy. Low carbohydrate intake is unhealthy. But, moderate carbohydrate intake is “just right.”

Specifically, this study reported:

  • Moderate carbohydrate intake (50-55%) is healthiest. This is also the carbohydrate intake recommended by current nutritional guidelines.
  • All major studies agree that very high carbohydrate intake (60-70%) is unhealthy. It shortens life expectancy of a 50-year old by about a year.
  • All studies that cover the full range of carbohydrate intake agree that low carbohydrate intake (<40%) is also unhealthy. It shortens life expectancy of a 50-year old by about 4 years.
  • The studies quoted by low carb enthusiasts to support their claim that low-carb diets are healthy don’t include carbohydrate intakes below 40%. That means their claims are misleading. The studies they quote are incapable of detecting the risks of low carbohydrate diets.
  • Meat-based, low-carb diets decrease life expectancy while plant-based, low carb diets increase life expectancy. This is consistent with the results of previous studies.

The authors concluded: “Our findings suggest a negative long-term association between life-expectancy and both low carbohydrate and high carbohydrate diets…These data also provide further evidence that animal-based low carbohydrate diets should be discouraged. Alternatively, when restricting carbohydrate intake, replacement of carbohydrates with predominantly plant-based fats and proteins could be considered as a long-term approach to healthy aging.”

For more details, read the article above.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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Does Magnesium Optimize Vitamin D Levels?

Posted February 12, 2019 by Dr. Steve Chaney

The Case For Holistic Supplementation

Author: Dr. Stephen Chaney

 

Does magnesium optimize vitamin D levels?

magnesium optimize vitamin dOne of the great mysteries about vitamin D is the lack of correlation between vitamin D intake and blood levels of its active metabolite, 25-hydroxyvitamin D. Many people who consume RDA levels of vitamin D from foods and/or supplements end up with low blood levels of 25-hydroxyvitamin D. The reason(s) for this discrepancy between intake of vitamin D and blood levels of its active metabolite are not currently understood.

Another great mystery is why it has been so difficult to demonstrate benefits of vitamin D supplementation. Association studies show a strong correlation between optimal 25-hydroxyvitamin D levels and reduced risk of heart disease, cancer, and other diseases. However, placebo-controlled clinical trials of vitamin D supplementation have often come up empty. Until recently, many of those studies did not measure 25-hydroxyvitamin D levels. Could it be that optimal levels of 25-hydroxyvitamin D were not achieved?

The authors of the current study hypothesized that optimal magnesium status might be required for vitamin D conversion to its active form. You are probably wondering why magnesium would influence vitamin D metabolism. I had the same question.

The authors pointed out that:

  • Magnesium status affects the activities of enzymes involved in both the synthesis and degradation of 25-hydroxyvitamin D.
  • Some clinical studies have suggested that magnesium intake interacts with vitamin D intake in affecting health outcomes.
  • If the author’s hypothesis is correct, it is a concern because magnesium deficiency is prevalent in this country. In their “Fact Sheet For Health Professionals,” the NIH states that “…a majority of Americans of all ages ingest less magnesium from food than their respective EARs [Estimated Average Requirement]; adult men aged 71 years and older and adolescent females are most likely to have low intakes.” Other sources have indicated that magnesium deficiency may approach 70-80% for adults over 70.

If the author’s hypothesis that magnesium is required for vitamin D activation is correct and most Americans are deficient in magnesium, this raises some troubling questions.

  • Most vitamin D supplements do not contain magnesium. If people aren’t getting supplemental magnesium from another source, they may not be optimally utilizing the vitamin D in the supplements.
  • Most clinical studies involving vitamin D do not also include magnesium. If most of the study participants are deficient in magnesium, it might explain why it has been so difficult to show benefits from vitamin D supplementation.

Thus the authors devised a study (Q Dai et al, American Journal of Clinical Nutrition, 108: 1249-1258, 2018 ) to directly test their hypothesis.

 

How Was The Study Designed?

magnesium optimize vitamin d studyThe authors recruited 180 volunteers, aged 40-85, from an ongoing study on the prevention of colon cancer being conducted at Vanderbilt University. The duration of the study was 12 weeks. Blood was drawn at the beginning of the study to measure baseline 25-hydroxyvitamin D levels. Three additional blood draws to determine 25-hydroxyvitamin D levels were performed at weeks 1, 6, and 12.

Because high blood calcium levels increase excretion of magnesium, the authors individualized magnesium intake based on “optimizing” the calcium to magnesium ratio in the diet rather than giving everyone the same amount of magnesium. The dietary calcium to magnesium ratio for most Americans is 2.6 to 1 or higher. Based on their previous work, they considered an “ideal” calcium to magnesium ratio to be 2.3 to 1. The mean daily dose of magnesium supplementation in this study was 205 mg, with a range from 77 to 390 mg to achieve the “ideal” calcium to magnesium ratio. The placebo was an identical gel capsule containing microcrystalline cellulose.

Two 24-hour dietary recalls were conducted at baseline to determine baseline dietary intake of calcium and magnesium. Four additional 24-hour dietary recalls were performed during the 12-week study to assure that calcium intake was unchanged and the calcium to magnesium ratio of 2.3 to 1 was achieved.

In short this was a small study, but it was very well designed to test the author’s hypothesis.

 

Does Magnesium Optimize Vitamin D Levels?

 

does magnesium optimize vitamin d levelsThis was a very complex study, so I am simplifying it for this discussion. For full details, I refer you to the journal article (Q Dai et al, American Journal of Clinical Nutrition, 108: 1249-1258, 2018).

The most significant finding was that magnesium supplementation did affect blood levels of 25-hydroxyvitamin D. However, the effect of magnesium supplementation varied depending on the baseline 25-hydroxyvitamin D level at the beginning of the study.

  • When the baseline 25-hydroxyvitamin D was 20 ng/ml or less (which the NIH considers inadequate), magnesium supplementation had no effect on 25-hydroxyvitamin D levels.
  • When the baseline 25-hydroxyvitamin D was 20-30 ng/ml (which the NIH considers the lower end of the adequate range), magnesium supplementation increased 25-hydroxyvitamin D levels.
  • When the baseline 25-hydroxyvitamin D level approached 50 ng/ml (which the NIH says may be “associated with adverse effects”), magnesium supplementation lowered 25-hydroxyvitamin D levels.

The simplest interpretation of these results is:

  • When vitamin D intake is inadequate, magnesium cannot magically create 25-hydroxyvitamin D from thin air.
  • When vitamin D intake is adequate, magnesium can enhance the conversion of vitamin D to 25-hydroxyvitamin D.
  • When vitamin D intake is too high, magnesium can help protect you by lowering 25-hydroxyvitamin D levels.

The authors concluded: “Our findings suggest that optimal magnesium status may be important for optimizing 25-hydroxyvitamin D status. Further dosing studies are warranted…”

 

What Does This Study Mean For You?

magnesium optimize vitamin d for youThis was a groundbreaking study that has provided novel and interesting results.

  • It provides the first evidence that optimal magnesium status may be required for optimizing the conversion of vitamin D to 25-hydroxyvitamin D.
  • It suggests that optimal magnesium status can help normalize 25-hydroxyvitamin D levels by increasing low levels and decreasing high levels.

However, this was a small study and, like any groundbreaking study, has significant limitations. For a complete discussion of the limitations and strengths of this study I refer you to the editorial (S Lin and Q Liu, American Journal of Clinical Nutrition, 108: 1159-1161, 2018) that accompanied the study.

In summary, this study needs to be replicated by larger clinical studies with a more diverse study population. In order to provide meaningful results, those studies would need to carefully control and monitor calcium, magnesium, and vitamin D intake. There is also a need for mechanistic studies to better understand how magnesium can both increase low 25-hydroxyvitamin D levels and decrease high 25-hydroxyvitamin D levels.

However, assuming the conclusions of this study to be true, it has some interesting implications:

  • If you are taking a vitamin D supplement, you should probably make sure that you are also getting the DV (400 mg) of magnesium from diet plus supplementation.
  • If you are taking a calcium supplement, you should check that it also provides a significant amount of magnesium. If not, change supplements or make sure that you get the DV for magnesium elsewhere.
  • I am suggesting that you shoot for the DV (400 mg) of magnesium rather than reading every label and calculating the calcium to magnesium ratio. The “ideal” ratio of 2.3 to 1 is hypothetical at this point. A supplement providing the DV of both calcium and magnesium would have a calcium to magnesium ratio of 2.5, and I would not fault any manufacturer for providing you with the DV of both nutrients.
  • If you are taking high amounts of calcium, I would recommend a supplement that has a calcium to magnesium ratio of 2.5 or less.
  • If you are considering a magnesium supplement to optimize your magnesium status, you should be aware that magnesium can cause gas, bloating, and diarrhea. I would recommend a sustained release magnesium supplement.
  • Finally, whole grains and legumes are among your best dietary sources of magnesium. Forget those diets that tell you to eliminate whole food groups. They are likely to leave you magnesium-deficient.

Even if the conclusions of this study are not confirmed by subsequent studies, we need to remember that magnesium is an essential nutrient with many health benefits and that most Americans do not get enough magnesium in their diet. The recommendations I have made for optimizing magnesium status are common-sense recommendations that apply to all of us.

 

The Case For Holistic Supplementation

 

magnesium optimize vitamin d case for holistic supplementationThis study is one of many examples showing that a holistic approach to supplementation is superior to a “magic bullet” approach where you take individual nutrients to solve individual problems. For example, in the case of magnesium and vitamin D:

  • If you asked most nutrition experts and supplement manufacturers whether it is important to provide magnesium along with vitamin D, their answer would likely be “No”. Even if they are focused on bone health, they would be more likely to recommend calcium along with vitamin D than magnesium along with vitamin D.
  • If your doctor has tested your 25-hydroxyvitamin D levels and recommended a vitamin D supplement, chances are they didn’t also recommend that you optimize your magnesium status.
  • Clinical studies investigating the benefits of vitamin D supplementation never ask whether magnesium intake is optimal.

That’s because most doctors and nutrition experts still think of nutrients as “magic bullets.” I cover holistic supplementation in detail in my book “Slaying The Supplement Myths.”  Other examples that make a case for holistic supplementation that I cover in my book include:

  • A study showing that omega-3 fatty acids and B vitamins may work together to prevent cognitive decline. Unfortunately, most studies looking at the effect of B vitamins on cognitive decline have not considered omega-3 status and vice versa. No wonder those studies have produced inconsistent results.
  • Studies looking at the effect of calcium supplementation on loss of bone density in the elderly have often failed to include vitamin D, magnesium, and other nutrients that are needed for building healthy bone. They have also failed to include exercise, which is essential for building healthy bone. No wonder some of those studies have failed to find an effect of calcium supplementation on bone density.
  • A study reported that selenium and vitamin E by themselves might increase prostate cancer risk. Those were the headlines you might have seen. The same study showed Vitamin E and selenium together did not increase prostate cancer risk. Somehow that part of the study was never mentioned.
  • A study reported that high levels of individual B vitamins increased mortality slightly. Those were the headlines you might have seen. The same study showed that when the same B vitamins were combined in a B complex supplement, mortality decreased. Somehow that observation never made the headlines.
  • A 20-year study reported that a holistic approach to supplementation produced significantly better health outcomes.

In summary, vitamins and minerals interact with each other to produce health benefits in our bodies. Some of those interactions we know about. Others we are still learning about. When we take high doses of individual vitamins and minerals, we create potential problems.

  • We may not get the full benefit of the vitamin or mineral we are taking because some other important nutrient(s) may be missing from our diet.
  • Even worse, high doses of one vitamin or mineral may interfere with the absorption or enhance the excretion of another vitamin or mineral. That can create deficiencies.

The same principles apply to our diet. I mentioned earlier that whole grains and legumes are among the best dietary sources of magnesium. Eliminating those two foods from the diet increases our risk of becoming magnesium deficient. And, that’s just the tip of the iceberg. Any time you eliminate foods or food groups from the diet, you run the risk of creating deficiencies of nutrients, phytonutrients, specific types of fiber, and the healthy gut bacteria that use that fiber as their preferred food source.

The Bottom Line

 

A recent study suggests that optimal magnesium status may be important for optimizing 25-hydroxyvitamin D status. This is one of many examples showing that a holistic approach to supplementation is superior to a “magic bullet” approach where you take individual nutrients to solve individual problems. For example, in the case of magnesium and vitamin D:

  • If you asked most nutrition experts and supplement manufacturers whether it is important to provide magnesium along with vitamin D, their answer would likely be “No.”  Even if they are focused on bone health, they would be more likely to recommend calcium along with vitamin D than magnesium along with vitamin D.
  • If your doctor has tested your 25-hydroxyvitamin D levels and recommended a vitamin D supplement, chances are he or she did not also recommend that you optimize your magnesium status.
  • Clinical studies investigating the benefits of vitamin D supplementation never ask whether magnesium intake is optimal. That may be why so many of those studies have failed to find any benefit of vitamin D supplementation.

I cover holistic supplementation in detail in my book “Slaying The Supplement Myths” and provide several other examples where a holistic approach to supplementation is superior to taking individual supplements.

In summary, vitamins and minerals interact with each other to produce health benefits in our bodies. Some of those interactions we know about. Others we are still learning about. Whenever we take high doses of individual vitamins and minerals, we create potential problems.

  • We may not get the full benefit of the vitamin or mineral we are taking because some other important nutrient(s) may be missing from our diet.
  • Even worse, high doses of one vitamin or mineral may interfere with the absorption or enhance the excretion of another vitamin or mineral. That can create deficiencies.

The same principles apply to what we eat. For example, whole grains and legumes are among the best dietary sources of magnesium. Eliminating those two foods from the diet increases our risk of becoming magnesium deficient. And, that’s just the tip of the iceberg. Any time you eliminate foods or food groups from the diet, you run the risk of creating deficiencies.

For more details about the current study and what it means to you read the article above.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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